Gripper mechanism



J. FOSSA GRIPPER MECHANISM June 14, 1949.

5 Sheets-Sheet 1 Filed Feb. 26, 1947 lnvenfar Joseph Foam Filed Feb. 26,1947 3 Sheets-Sheet 2 QAN [nizmfar Joseph Fossa' Patented June 14, 1949UNITED STATES PATENT OFFICE GRIPPER IWECHANISM Joseph Fossa, Hamilton,Mass., assignor to United Shoe Machinery Corporation, Flemington, N. J.,a corporation of New Jersey Application February 26, 1947, Serial No.730,978

14 Claims. (01. 12-1) This invention relates to gripper mechanism andthe herein illustrated embodiment thereof is shown applied to a lastingmachine of the type disclosed in United States Letters Patent No.2,411,827, issued in my name on November 26, 1946. It will beunderstood, however, that the novel gripper mechanism of this inventionis not limited in its utility to use in a lasting machine or toapplication to a lasting machine of the exact construction exemplifiedin the aforementioned patent.

In the machine of the mentioned patent, the stock is tensionedsuccessively, in different locations along the edge of the bottom of theshoe, by means of gripper mechanism comprising a pair of jaws which,after closing on the lasting margin of the stock, draw the lastingmargin inwardly from the edge of, and over, the shoe bottom, and thetensioned stock is pressed against the shoe bottom, in each location, bymeans of a presser feed foot which is also operable to feed the shoe, aswell as by a feed retainer that serves to hold the shoe againstretrograde movement during the back-feeding movement of the presser feedfoot. In this prior mechanism, the gripper jaws are yieldingly closed onthe lasting margin,

through the action of a spring, and thereafter are positively moved totension the stock which will slip through the yieldingly closed jawswhen the pull exerted thereon exceeds the frictional grip of the jaws.As will be apparent, this frictional grip, which may be intentionallymodified, to suit different operating conditions, by adjusting thetension of the gripper-closing spring, will also change with thethickness of the stock, the character of the surfaces of thestockengaged by the jaws as well as with the nature of the operating faces ofthese jaws. Thus, the amount of pull applied may vary, at differentlocations along the edge of the bottom of a shoe, as stock of differentthicknesses or of different characters 'is encountered. Moreover, uponcontinued use it has been found that the operating surfaces of thegripper jaws, which in accordance with a usual practice would beroughened to enhance their frictional effect, sometimes becomesmoothened by the abrasive action of material in the stock so that theirfrictional grip is considerably lessened. While the variation in thepull applied to the stock which mayresult from any of the above reasonsis ordinarily not sufiicient adversely to affect thelasting operation,it is desirable and preferable that the amount of pull applied beuniform. atall locations along the edge of the .bottomof the shoe. Th sis especially true in the so-called platform cover-lasting operationwhere the pull applied to the cover by the gripper not only tensions thecover but also compresses the yieldable platform member somewhat. Underthese conditions, a variation in the amount of pull may result in acorresponding variation in the thickness of the platform which would bevisible in the completed shoe.

It is, therefore, an object of this invention to provide a novel andimproved gripper mechanism by means of which a substantially uniform,yet selectively variable pull may be obtained. With this end in view,and in accordance with a feature of this invention, the hereinillustrated gripper mechanism has a first jaw which is yieldinglymovable in a direction to tension the stock, a second jaw which isreciprocated toward and away from the first jaw, and cooperating cammeans associated with these jaws arranged to effect a relative closingmovement of these jaws on the stock and, thereafter, movement of thefirst law by, and together with, the second jaw, in a direction totension the stock. More particularly, these jaws each are provided withtoothed operating faces so that when closed on the stock, by the actionof the cam means, they grip it positively, regardless of thethickness orcharacter of the stock, and, in accordance with a further feature of theinvention, the second jaw is moved toward the first jaw through springmeans, which are arranged to be adjusted to vary the amount of the pullapplied, and is positively moved away from the first jaw. Also, and inaccordance with a still further feature of the invention, means areprovided for intermittently locking and unlocking the first jaw in timerelation to the reciprocating movements of the second jaw so that thejaws, successively, grip, tension and release the stock during eachreciprocation of the second position assumed during the operation of thema- .chine;

Fig. 3 is a view in front elevation of a portion ofthe machine shown inFig. 1;

Fig. 4 is a view in front elevation and at an enlarged scale showing theoperating elements only of the machine and with certain parts shown insection;

Fig. 5 is a section, on line V-V of Fig. 2, of a portion of the grippermechanism; and

Figs. 6 and 7 are sectional views, taken on line VI-VI and line VII-VIIof Fig. 2, respectively, and showing certain details of construction ofthe gripper mechanism.

Referring to the drawings, the improved gripper mechanism is thereinillustrated as applied to a lasting machine which is similar to thatdisclosed in my aforementioned patent. The operating elements of thismachine comprise arear gripper jaw It, a front gripper jaw I2, acombined shoebottom rest and lasting shield 14, a presser feed foot I6,a feed-retaining finger I8 and an edge gage roll 20. These variouselements are'supported on, and operated by mechanism contained within, ahollow head construction 22 having a lower portion 24 and an upperremovable cover part 26. Inasmuch as the mechanisms for operating thepresser feed foot I6 and feed-retaining finger I8 from a main powershaft 28, mounted in the head 22, is of no particular significance sofar as the present invention is concerned and is fully disclosed anddescribed in my prior patout, these mechanisms have been omitted fromthe drawings for the sake of clarity. Also, in

closure of the improved gripper mechanism. With the exception of thegripper mechanism, the herein illustrated machine operates in the samemanner as the machine of my prior patent to tension the stock to belasted, by drawing its lasting margin inwardly from the edge of thebottom of the shoe, to press the lasting margin of the tensioned stockagainst the shoe bottom and to feed the shoe.

In the machine illustrated in the drawings, the shoe-bottom rest I4 ismounted for movement to and from the operating position in which it isshown in the following manner. The shoe-bottom rest is secured, byscrews 39, to the lower end of a lever (H which is rotatably mounted ona cross shaft 32 carried by a forwardly projecting portion of the cover26. At its upper end, this arm is adjustably secured, by means of ascrew 34 and slot 36, to an arm 38 which is likewise rotatably mountedon the shaft 32, and connected to this arm is a link 40 which is pinnedto the end of a rocker arm 42 secured to a shaft 44. Also secured to theshaft 44, outside of the cover 26, is a second rocker arm 46 to which isconnected a treadle rod 48. In Figs. 1 and 2 of the drawings, thistreadle rod is shown as lowered, against the action of a spring, notshown, so as to straighten the toggle formed by the link 40 andtherocker arm 42 thereby to swing the lever 38 in a counterclockwisedirection and move the shoe-bottom rest I4 to its operating position asshown. When the treadle, not shown, is released, the rod 48 will beelevated by the spring, also not shown, and the toggle broken, thusswinging the lever 38 in a clockwise direction and shifting theshoe-bottom rest to its inoperative position.

Referring now to the gripper mechanism with which this invention isconcerned, the rear gripper jaw I0 is carried by an elongated arm 50which is pivotally connected to the left-hand end of a rod 52. This rodis slidable in guideways 54, 56 formed in upstanding portions 58, 60rising from a carrier 62. At its right-hand end, this rod is clamped, bymeans of a screw 66, to a block 64 which at its upper portion isprovided with an ear 68, see Fig. '7. This ear is confined within a slotI0, formed on a rearwardly proj ecting part of the upstanding portion60, so as to prevent rotation of the rod 52 while permitting this rod toslide longitudinally in the guideways 54, 56. Passing through the block64, and posi-- tioned on opposite sides of the upstanding portion 60,are two rods I4, I4, see Fig. 7. Each of these rods has a rearwardly anddownwardly inclined end portion I6, see Figs. 1 and 2, and each rod issecured to the block 64 by means of a setscrew I8. The rods 52 and 14also pass through and support a block of cushioning material 69 which isinterposed between the upstanding portion 60 and the block 64.

The rod 52 is urged yieldingly and to the left, relatively to thecarrier 62, by means of a pair of tension springs 80, 80, see Fig. 6,each of these springs being stretched between the downturned end I6 ofone of the rods 14 and an adjustable anchor block 82, see Figs. 1, 2 and6. This anchor block has a bifurcated upper end which embraces acrossbar 84, extending between the upstanding portions 58 and 60 andsecured to the latter by a screw 86, and a lower end which is slotted at88 to straddle the rod 52, see Fig. 6. Secured to the block 82 is athreaded stud 90 which extends to the left, as viewed in Figs. 1 and 2,,and through a clearance hole 92 formed in the upstanding portion 58.Threaded on to this stud is an adjusting sleeve 94 which has an enlargedand 86 adapted to seat on a shoulder 88 formed in the hole 92. Thesleeve 94 is provided with a slot I00 for receiving a screw driver, orother suitable tool,

; for rotating the sleeve to shift the anchor block 82 to the right orto the left, thereby decreasing or increasing the tension of the spring;at. The upstanding portion 60 limits movement of the block 82 to theright end, to prevent the sleeve 94 from being wholly unscrewed from thestud 90 after this limit of movement of the anchor block 82 has beenreached, a. stop Hi2, Secured to the crossbar 84 by means of a screwI04, 15. arranged to engage the enlarged portion 98 on the sleeve 94.

The carrier 52 is supported on two rocker arms H0, H2 and during theoperation or the machine is reciprocated by means of an eccentric H4,carried by the main shaft 28, the motion of which is transmitted to throcker arm Hz by means of a connecting rod H6 and a third rocker arm I I8 which is connected to the rocker arm H2. As will be apparent byreference to the above-mentioned patent, the above arrangement forsupporting and reciprocating the carrier 62 of the herein illustratedmachine is similar to that provided in the machine of the patent forsupporting and reciprocating the carrier 32.

The arm 38 isprovided with a depending lug $30 anda rearwardly extendingshoulder I32. Pivotally supported onthe lug I38, bymeans of a pin 134,is an angular lever I36 having a forwardly and downwardly extending armI38, 21 rearwardly extending portion H0 and a flat abutment surface I42.A coil spring I 44, stretched between the arm 38 and the rearwardl-yextending portion I40, tends to hold thelever I-39 in the position inwhich it is shown in Fig. 1. and with the abutment surface I42 pressedagainst a block I46 of cushioning material such, for example, as rubberor'l'eatherwhich is fitted into a dovetail re.

cess formed in the shoulder I32. The front gripper jaw I2 has anupturned portion I48'which fits snugly between two ears I50, I52 formedon the arm I38 of the lever I30, and beneath a pin I54 which passesthrough these two ears, see Fig. 3. The upper end of the portion I48 ofthe front gripper jaw is slotted at I 56 to receive a clamping screwI58. When this clamping screw is loosened, the front gripper jaw may beadjusted vertically with respect to the rear gripper jaw I in a-man nerwhich should be readily apparent.

Pivotally connected to the arm I38, by means of a pin I60 and clevisblock I62, is a locking rod I64. This rod extends rearwardly of themachine and passes through clearance holes I86, I68 formed in theupstanding portions 58 and 60, re"- spectively, the hole 88 in the block82, a clearance hole I in the block 64 and between two locking blocksI12, I14. These two locking blocks are fitted in a recess I of a housingI16, which pro-' jects upwardly from a web I18 formed integrall with thelower head portion 24, and are grooved at I80, I82, see Fig. 5, toreceive the locking rod I64. The blocks I12, I14 are supported on aneccentric I84 which is formed integrally with a lever I86, thiseccentric engaging a recess I81 in the lower block I14. The upper blockI12 is urged downwardly by an adjusting screw I93, threaded through thehousing I16, and is held against longitudinal movement, relatively tothe housing, by means of flanges I88, I90 thereon.

The lever I86 is rotatably mounted on a pin I9I and has a cam portionI92 which, at times, is adapted to be engaged by a roll I94 toward whichthe lever I86 is swung by means of a coil spring I96. This coil springis stretched between a pin I98, carried by the lever I86 and a bracket200 which is supported on a pin 202, carried by the housing, and heldagainst rotation under the pull of the spring by engagement with the pinI9I. The roll I94 is mounted on a bell-crank lever 204 which isoscillated from the eccentric II4 by means of a connecting rod 206, arocker arm 208 and a link 2I0. The rod I64 also extends through a notch2I-2, cut in an upwardly extending projection 2I4 on the lever I86 andis provided with a threaded end for receiving a nut 2| 6.

Journaled on a stud 220, carried by the lever I36, is a grooved roll 222which is directly in line with the rear gripper jaw I 0. This jaw has aninclined portion facing the roll which is provided with a rib 224adapted to cooperate with'this grooved roll when the rear jaw isadvanced toward the front jaw by the reciprocation of the carrier 62. Asshown in Fig. 1, when the rear jaw is withdrawn from the front jaw, thearm 50 iselevated by means of a leaf spring 228 to the extent permittedby the engagement of the rear jaw with a flat surface 230 formed on thelower side of the clevis block I62.

The operation of the gripper mechanism will now be described. Referringto Fig.1, the carrier 62 is in its extreme limit of movement to theright and the rear gripper jaw I0 is separated from the front gripperjaw I2 as shown. Also, the lever I86 has been rotated, in acounterclockwise direction by the engagement of the roll I94 with aportion of the camsurface I 92 so as to relieve the clamping pressure ofthe eccentric I84 on the blocks I12, I14 thus releasing the rod I64 andpermitting spring 144 to swing the lever I36 .in a counterclockwisedirection until surface I42 bears against the cushioning block I48.Inasmuch as the treadle (not shown) is now depressed, the front gripperjaw I2 will beyieldingly. held'in' the position shown in Fig. 1 by thespring I44. As the shaft 28 rotates, in the direction of the arrow,

the carrier 62 will be moved to the left and with the last L, is firmlygripped between the operating faces of the two jaws I0 and I2.Preferably, and as herein illustrated, the operating faces of these twojaws are provided, respectively, with intermeshing teeth 23I, 232 toaugment their gripping action. Accordingly, and as a result of therelative approaching movement of the operating faces of the jaws I9 andI2, caused by the camming effect of the inclined rib 224 on the roll222, the lasting margin of the cover C will be seized with a positive,non-slipping grip.

As the carrier 62 continues its movement to the left, after the lastingmargin of the cover 0 has been gripped by the jaws I0 and I2 in themanner explained above, the spring I44 yields, thus permitting the leverI36 to rotate in a clockwise direction about the pin I34. Accordingly,the two jaws I0 and I2 now move together, as a unit and to the left, totension the cover by drawing its lasting margin inwardly from the edgeof the bottom of the platform P and over the shoebottom rest I4. Fig. 2shows the operating parts of the machine in the positions assumed at thecompletion of the tensioning action and after the shaft 28 has rotated180 from the position shown in- Fig. l. The amount of tension applied tothe cover C by the gripper jaws I0 and I2 is determined by the springsthrough which movement of the carrier to the left is transmitted to therod 52 and to the arm 50 which carries the jaw I0. Therefore, when thispredetermined amount of tension has been applied, these springs willyield and movement of the jaw I0 will be terminated, the block 64 nowseparating from the cushioning block 69, in the manner shown in Fig. 2,in response to the continued movement of the carrier 62.

As'the shaft 28 continues to turn, the bellcrank lever 204 is rotated ina counterclockwise direction to cause the roll I 94 to travel along thecam surface I92 to a position thereon in which the spring I can turn thelever I86 in a clockwise direction so that the eccentric I84 will beeffective to apply clamping pressure on the rod I64 through the blocksI12, I14. With this rod thus locked, the lever I36 is held againstmovement by the spring I44 so that the front jaw I2 is held in theposition in which it is shown in Fig. 2 as the rear jaw is movedreversely to release the cover C during the return reciprocation of thecarrier 62. Just as this return reciprocation of the car-rier iscompleted, the roll I94 again assumes a position on the cam surface I92in which the lever I86 is turned so as to relieve the clamping pressureof the blocks I12, "4 on the rod I64. With this rod thus unlocked,spring I44 swings the lever I36 back to the position in which surfaceI42 thereon bears against the cushioning block I46, as shown in Fig. l.

, From the above, it will be seen that in each cycle of operation of thegripper mechanism,

effected by a complete reciprocation of the carrier 62 and jaw- I0, thejaws I0 and I2 are first fclosed tog'rip the cover C firmly, then movedtogether, and as a unit, to apply a yielding; pull the presserteed footIt which thereafter moves to feed the shoe to present the nextsucceeding portion: of the cover to the action of. the grippers. Alsothefeed-retaining finger l8 operates to hold the shoe against retrogrademovement during the back-feeding motion of the presser-feed. foot.

. When the treadle is released and the toggle formed by link 40 androcker arm 42 broken, arm 38 and lever at will be rotated in a clockwisedirection to move the shoe bottom rest ll outwardly and upwardly to itsinoperative position.

During this movement of the arm 38, the coshioning block Hiwill engagethe surface I42 on the. lever I38 and, when the rod I64 has beenunlocked, this lever will move with the. army 38, thus shifting the jawI2 and cam rol-l 2'22 beyond the rangeof movement of the jaw Ill. Thenet M6,, threaded on the rod. I64, is so positioned, when the treadle isreleased and the arm 38 and lever L36 moved together in the abovemanner, as to. engage the lever Hi5 and swing. it, ina counterclockwisedirection, sufficiently to hold the. cam surface I52 separated fromthe.- roll I34. Thus, wearing of this camsurface, as wellas of theeccentric me, while the machine is permitted to run idly, is avoided.

Having described the invention, what I. claim as new and desire tosecure by Letters Patent of the United States is:

1.. A gripper mechanism comprising a first. jaw, yieldingly movable ina. direction to tension the stock and; having an operating face forengaging oneside of the. lasting margin of the. stock, a second jawhaving an operating face for engaging' the opposite side of the lastingmargin, means for reciprocating said second jaw toward and away fromsaid first jaw, and cooperating means associated with said jawsconstructed andarranged, upon movement of the second jaw in a directiontoward the first jaw, to effect relative approaching movement of saidoperating faces for gripping the lasting margin and,v thereafter, tocause movement of said first jaw by, and together with, said second jaw,for tensioning the stock.

2. A gripper mechanism comprising a. first jaw, yield-ingly movable in adirection to tension the stock and having an operating face for engagingone side of the lasting margin. of the stock, a second jaw having anoperating, face for engaging the opposite side of the lasting margin,means for reciprocating said second jaw toward and awayfrom said firstjaw, and cooperating; cam means associated with saidjaws constructed andarranged, upon movement of the second law in a direction toward thefirst jaw, to effect relative approaching movement of said operatingfaces for gripping the lasting margin and, thereafter, to cause movementof said first jaw by, and together with, said second jaw for tensioningthe stock.

3. A gripper mechanism comprising a first jaw, yieldingly movable in adirection. to tensionv the stock and having an operating face forengaging one side of the lasting, margin of the stock, a second jawhaving an operating facefor engag- ,ing the opposite side of the lastingmargin, means to: reciprocating said second jaw toward and away fromsaid first jaw, cooperating means associated with. said j aws,constructed and arranged, upon. movement of thesecond jaw in a directiontoward. the first jaw, to effect relative approaching movement of said.operating surfaces for gripping the. lasting margin and, thereafter, tocause movement of said first'jaw by, and together with, said. second jawina direction to tension the stock; and means associated with said firstjaw for preventing retrograde movement thereof during reciprocation ofsaid second jaw in the opposite. direction, thereby to release the stockafter it. hasbeen thus tensioned.

4.. Agripper mechanism comprising a first jaw, yieldingly movable in adirection to tension the stock and having anoperating face for engagingone side of the lasting margin of the stock, a secand. jawhaving. anoperating face for engaging the opposite side of the lasting margin,means for reciprocating said second jaw toward and away from said firstjaw, cooperating cam means associated. with said jaws constructed andarranged, upon movement of the second jaw in a direction toward thefirst jaw, to effect relative approaching movement of said operatingsurfaces for gripping the lasting margin, and, thereafter, to. causemovement of said first jaw by, and together with, said second jaw in adirection to tension the stock, and means associated with said jaw forpreventing retrograde movement thereof during reciprocation of saidsecond jaw in. the opposite direction, thereby to release the stockafter it has been thus tensioned.

'5. Agripper mechanism comprising a first jaw, yieldingly movable. inv adirection to tension the stock and having an. operating face forengaging one side of the lasting margin of the. stock, a second jawhaving an operating face for engaging the opposite side of the lastingmargin, means for reciprocating. said second jaw toward and away fromsaid-.firstajaw, cooperating means associated with. said jawsconstructed and arranged, upon movementiof the second jaw in a directiontoward the first jaw, to effect relative approaching movement: of said:operating surfaces for gripping the lasting margin. and, thereafter, tocause movement of said first jaw by, and together with, said second: jawin a direction to tension the stock, and means for intermittentlylocking and unlocking said first jaw in time relation to thereciprocating movements of said second jaw, thereby to cause said jawssuccessively to grip, tension and release the stock during eachreciprocation of said first jaw.

6. lag-ripper mechanism comprising a first jaw, yieldingly movable in adirection to tension the stock. and having an operating face forengaging one side of the lasting margin of the stock, a second jawhaving an operating face for engaging the opposite side of the lastingmargin, means for reciprocating said second jaw toward and away fromsaid first jaw, cooperating cam means associated with said jawsconstructed and arranged, upon movement of the second jaw in a directiontoward the. first jaw, to effect relative approaching movement of saidoperating surfaces for gripping the lasting margin, and, thereafter, tocansemovementiof said first jaw by, and together with, said second jawin a direction to tension the stock, and means for intermittentlylocking and unlocking said first jaw in time relation to thereciprocating movements of said second jaw, thereby to cause sai'djawssuccessively to grip, tensionandrelease the stock during eachreciprocation or said first jaw.

7. A gripper mechanism comprising a first jaw, yieldingly movable in adirection to tension the stock and having an operating face for engagingone side of the lasting margin of the stock, a second jaw having anoperating face for engaging the opposite side of the lasting margin,means for reciproating said second jaw yieldingly toward and positivelyaway from said first jaw, and cooperating means associated with saidjaws constructed and arranged, upon movement of the second jaw in adirection toward the first jaw, to effect relative approaching movementof said operating faces for gripping the lasting margin and, thereafter,to cause movement of said first jaw by, and together with, said secondjaw for tensioning the stock.

8. A gripper mechanism comprising a first jaw, yieldingly movable in adirection to tension the stock and having an operating face for engagingone side of the lasting margin of the stock, a second jaw having anoperating face for engaging the opposite side of the lasting margin,means for reciprocating said second jaw yieldingly toward and positivelyaway from said first jaw, and cooperating cam means associated with saidjaws constructed and arranged, upon movement of the second jaw in adirection toward the first jaw to effect relative approaching movementof said operating faces for gripping the lasting margin and, thereafter,to cause movement of a said first jaw by, and together with, said secondjaw for tensioning the stock.

9. A gripper mechanism comprising a first jaw, yieldingly movable in adirection to tension the stock and having an operating face for engagingone slide of the lasting margin of the stock, a second jaw having anoperating face for engaging the opposite side of the lasting margin,means for reciprocating said second jaw including adjustable springmeans for moving said second jaw toward said first jaw and positivemeans for moving said second jaw away from said first jaw, andcooperating means associated with said jaws constructed and arranged,upon movement of the second jaw in a direction toward the first jaw, toeffect relative approaching movement of said operating faces forgripping the lasting margin and, thereafter, to cause movement of saidfirst jaw by, and together with, said second jaw for tensioning thestock.

10. A gripper mechanism comprising a first jaw, yieldingly movable in adirection to tension the stock and having an operating face for engagingone side of the lasting margin of the stock, a second jaw having anoperating face for engaging the opposite side of the lasting margin,means for reciprocating said second jaw including adjustable springmeans for moving said second jaw toward said first jaw and positivemeans for moving said second jaw away from said first jaw, andcooperating cam means associated with said jaws constructed andarranged, upon movement of the second jaw in a direction toward thefirst jaw, to effect relative approaching movement of said operatingfaces for gripping the lasting margin and, thereafter, to cause movementof said first jaw by, and together with, said second jaw for tensioningthe stock.

11. A gripper mechanism comprising a first jaw yieldingly movable in adirection to tension the stock and having a toothed operating face forengaging one side of the lasting margin of the stock, a second jawhaving a toothed operating face for engaging the opposite side of thelasting margin, means for reciprocating said second Jaw toward and awayfrom said first jaw, and co" operating means associated with said jawsconstructed and arranged, upon movement of the second jaw in a directiontoward the first jaw, to effect relative approaching movement of saidoperating faces for positively gripping the lasting margin and,thereafter, to cause movement of said first jaw by, and together with,said second jaw, for tensioning the stock.

12. A gripper mechanism comprising a first jaw yieldingly movable in adirection to tension the stock and having a toothed operating face forengaging one side of the lasting margin of the stock, a second jawhaving a toothed op erating face for engaging the opposite side of thelasting margin, means for reciprocating said second jaw toward and awayfrom said first jaw, and cooperating cam means associated with said jawsconstructed and arranged, upon movement of the second jaw in a directiontoward the first jaw, to effect relative approaching movement of saidoperating faces for positively gripping the lasting margin and,thereafter, to cause movement of said first jaw by, and together with,said second jaw, for tensioning the stock.

13. A gripper mechanism comprising a first jaw yieldingly movable in adirection to tension the stock and having a toothed operating face forengaging one side of the lasting margin of the stock, a second jawhaving a toothed operating face for engaging the opposite side of thelasting margin, means for reciprocating said second jaw includingadjustable spring means for moving said second jaw toward said first jawand positive means for moving said second jaw away from said first jaw,and cooperating means associated with said jaws constructed andarranged, upon movement of the second jaw in a direction toward thefirst jaw, to effect relative approaching movement of said operatingfaces for positively gripping the lasting margin and, thereafter, tocause movement of said first jaw by, and together with, said second jawfor tensioning the stock.

14. A gripper mechanism comprising a first jaw yieldingly movable in adirection to tension the stock and having a toothed operating face forengaging one side of the lasting margin of the stock, a second jawhaving a toothed operating face for engaging the opposite side of thelasting margin, means for reciprocating said second jaw includingadjustable spring means for mov ing said second jaw toward said firstjaw, and

, positive means for moving said second jaw away from said first jaw,and cooperating cam means associated with said jaws constructed andarranged, upon movement of the second jaw in a direction toward thefirst jaw, to effect relative approaching movement of said operatingfaces for positively gripping the lasting margin and, thereafter, tocause movement of said first jaw by, and together with, said second jawfor tensioning the stock.

JOSEPH FOSSA.

REFERENCES CITED The following referenices are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 507,550 Lombard Oct. 31, 13932,257,842 Elliott Oct. 7, 1941

